High-Power Charge/Discharge Properties of LiFePO₄/Carbon Composites with Various Carbon Materials

Electrochemical properties of LiFePO4/carbon composites with various carbon materials were investigated to achieve high-rate charge and discharge properties. LiFePO4/carbon composites were synthesized by a pyrolysis of a LiFePO4 precursor solution added with porous graphite or particulate carbon powders. The LiFePO4/porous-graphite composite had a microstructure in which LiFePO4 particles existed on carbon surface and within pores. The LiFePO4/particulate-carbon composite had a microstructure in which each carbon particle was covered with LiFePO4 fine particles. The LiFePO4/porous-graphite and the LiFePO4/particulate-carbon composite electrodes showed high discharge capacities of 69 and 30 mAh g-1 at a high current density of 4000 mA g-1. The high electronic conductivity in the LiFePO4/porous-graphite composite contributed to achieving the large discharge capacity at the high current density.